Differential recording dilatometer



J1me 0' 4 P. CHEVENARD 1,766,775

DIFFERENTIAL RECORDI NG DILATOMETER Filed April 23, 1926 '4 Sheets-Sheet 1 June 24,. 1930. P.'-CHEVENARD DIFFERENTIAL RECORDING DILAIOMETER Filed April 23, 1926 4 Sheets-Sheet 2 June 24,1930. P. CHEVENARD- 1,766,775

DIFFERENTIAL RECORDING DILATOMETER Filed April 23 1926 4 Sheets-Sheet 3 Jun 24, 1930.

P. CHEVENARD DIFFERENTIAL RECORDING DILATOMETER 4 Sheets-Shae Filed April 23. 1926 m E. *Q

I l I I I I l l I l I l l I I l n l l v l I l I I l l I I I I I I I I I l l l l I I .I

Patented June '24, 1930 UNITED STATES ,PATENT OFFICE PIERRE GHE'VENABD, OF IMPHY, FRANCE, ASSIGNOR TO- SOCIETE -ANONYME D'E COM- IENTBY, FOURCHAMBA' ULT & DECAZEVILLE, OF PARIS, FRANCE DIFFERENTIAL RECORDING DILATOMETEB Application filed April 23, 1926, Serial No. 104,130, and in France May 8, 1925.

The dilatometer, theobject of the present invention, which comprises a device ensuring the mechanical registering of the expansions, is derived from the registering differ ential dilatometer the object of a U. S. Patent in the applicants name N 0. 1,489,115. It combines the sensitiveness and accuracy of this apparatus with the substantial construction and the convenience of a mechanical registering device. The apparatus, which offers very little encumbrance, ma y be installed without any special precautions. Photographic manipulations are obviated, and the particular features of the dilatometcr curve can be observed during the registering. In this manner the experiment can be stopped as soon as the. desired phenomenon has been produced, and this will offer a great economy of time.

As in the differential dilatometer with photographic recording, the new dilatomcter automatically inscribes a curve whose co-ordinates are:

1. -The difierencexbetween the expansion of the sample to be studied and of a standard consisting of Pyros alloy, for example of the alloy described in U. S. Patent No. 1,489,116

raised to the'same temperature.

2.The expansion of the standard, which covers the axis of the abscissae and shows the common temperature of the two test bars.

The following description, with reference to the appended drawings which are given by way of example, clearly sets forth the manrfler in which the invention is carried into efect.

Figs. 1, 2 and 3 are respectively views in profile, in elevation and in plan, of the dila' tometer, theobject of the invention.

Fig. i is a sectional view of the tubes containing the test bars.

Fig. 5 is an elevational view of Fig. 4.

. Fig. 6 is a front detail view of the silica rods traversing the plate.

Fig. 7 is a view of the base from below. Fig. 8 is a front view of the levers transmitting the expansions. Fig. 9 is a section on the line 9-9 of Fig. 8.

Fig. 10 is a front view of the levers and of the tripod compounding their movements.

Fig. 11 is a section of the tripod.

Fig. 12 is a diagrammatic view of the electric mechanism ensuring the alternating motion of the board carrying the record paper.

The sample bar E and the standard bar E are enclosed in silica tubes T T (Fig. 4) said tubes are heated at the same time in an electric furnace, and the expansion of the bars is imparted to'the amplifying elements by the silica rods t 27 The silica tubes T T are mounted on a vertical plate 1 which is disposed upon the horizontal base 2 of the dilatometer, and the silica rods t t traverse the platel, as shown in Fig. 5. The ends or heads of the said rods are in contact with the push-pieces 3 and 4 (Figs. 3. and 5) which are mounted in the sleeve 5. Upon the plate 1 is mounted by means of the rods 7 and 8 (Figs. 2, 6 and 8) the cage 9 which is shown in front view in Fig. 8 and in section in Fig. 9. The said cage comprises four adjustable stoppieces 10 which are disposed according to two parallel lines and are in contact with the pointed'portions p p and p 112 of the levers L L (Figs. 8 and 10) said levers which are terminatedby the said pointed members comprise at the middle part the pointed portions 11 and 12 which are in contact with the push-pieces 3 and 4 (Figs. 2 and 9). Finally the levers L L, are terminated by tempered steel contact pieces g g Springs such as 13 (Fig. 2) maintain each of the levers L L in position.

The levers L L which are thus pivoted about the lines of the pointed portions 12 12 p forming lines of stationary points, will thus afford the first amplification, so that the contact pieces g 9 at the end of said levers will be displaced by a quantity which is respectively proportional to the expansion of each test bar E E These expansions are compounded by means of a tripod. B (Figs. 9 to 11) provided with the three sharp points a a a1 which are disposed at the vertices of a right-angled triangle (Fig. 10). The point a corresponding to the right angle is placed in a small recess 0 which is formed at the centre of the contact piece 9 (Fig. 8) the point a is in contact with the highly polished flat face of the contact piece g lastly the point (1 is engaged in a horizontal slot, not shown, provided at the end of a steel block H (Fig. 11) secure to the support 14 which is mounted on the plate 1 (Fig. 2). The said slot and the recess 0 which are disposed in line with the slot, will prevent all rotation of the tripod in its own plane. The springs 1' r 71, (Figs. 9 and 11) ensure the contact of these various parts. A needle A, terminated by a pen P carrying glycerine ink, is secured to the tripod B and is perpendicular to the plane of the three points a a a (Figs. 2 and 3).

The fork 30 having three branches, shown in Fig. 6,-serves as a spacing member, and is inserted below the heads of the rods 6 t during the assembling of the apparatus; said member limits the displacement of the sliding member to the left, and prevents the tripod from assuming angular displacements of an excessive amplitude.

When the test rods expand, the tripod B is subjected to a complex movement about the stationary point a This movement may be decomposed into two rotations whereof the first, which takes place about a horizontal axis a a is proportional to the difference in the expansion of the two test bars, and the second, about a vertical axis passing throu h a is proportional to the expansion of t e standard bar. The end of the pen P will thus describe, upon a sphere whose centre is a the curve of the differential expansion.

It is now required to register this spherical curve upon a sheet of ordinary paper, while entirely eliminating the friction which would be prejudicial to the delicacy of the curve.-

The solution of the problem consists in placing the sheet of paper upon a board D which is carried by a sliding element G, movable on the rails 15 and 16 (Figs. 2 and 3) on the base 2 and is given an alternating motion perpendicular to the mean direction of the needle A.

The pen is mounted at the end of a tube C which is slidable upon the needle A; said tube is urged outwardly by a sprin R, but its movement is limited by a pin 6 Fig. 2).

The amplitude of the alternatin motion imparted to the sliding element G is such that the pen ceases to bear upon the board D when the sliding element is at the end of its stroke; but when the board is dis laced to the left of Fig. 2, it meets with t e pen B and drives back the tube 0 upon the needle A, whilst a point is registered upon the paper. The curve is thus formed of a series of points which are sufliciently close together to form a continuous curve. Since after each recording of a point, all contact between the .pen and the paper ceases, the friction is entirely eliminated and the curve will show the smallgst' anomalies in the expansion of the sample ar. I To impart the alternative motion to the board, one may employ a mechanical device of any kind, and for example an eccentric controlled by clockwork or by an electric motor. But the motor operating by expansion which will be described hereinafter will afford very satisfactory results.

The board D is actuated by means of an arm'U, formed in one with a lever K which is disposed below the instrument base 2 (Figs. 7 and 12) and is pivoted about a vertical axis M M. To the end W of the lever K is attached a Wire F whose outer end is secured to a regulating screw V. To diminish the space occupied, the wire F is disposed on a pulley 17, so that the operative length of the wire is substantially double the length of the base 2.

The wire F is of an alloy of iron, nickel and chromium which is very expansible and very tenacious when hot; it may be heated by a electric current for which the make and break is controlled by a mercury drop switch I. The said switch is pivoted on a horizontal axis Q. The pivoting movement is controlled by an arm M S which is rigidly secured to the lever K; the regulating screw V which is disposed at the end of the lever M S is in contact with the arm Q, X mounted on the switch. I. The spring N, whose outer end is attached to the arm U, keeps the, wire F suitably stretched at all times. The switch I and the screw V are connected with the terminals 18, 19 of a suitable source of current (Fig. 12),

When the current passes, the wire F is heated by the Joule effect and thus expands. The change in length, amplified by the lever K, is transmitted by the arm U, and the board D which is urged by the spring N, will make contact with the pen P.

But this movement will cause the pivoting of the mercury switch I, due to the action of the screw V upon the arm X, so that the circuit will be broken. The said wire will be cooled and will thus contract, and the board will be brought to the rear, to a point at which the switch I is again closed, and the above-mentioned actions will proceed as before.

The screws V and V permit 'of regulatformed of isochronous dashes whose length represents a duration of four minutes, whilst the white space between the same will correspond to a duration of one minute.

Obviously, without departing from the spirit of the invention, it is susceptible of modifications in detail.

What I claim is:

1. A diflt'erential dilatometer comprising a device containing a standard piece an test piece, amplifying levers adapted to be acted upon by the said pieces, during expansion thereof, a tri 0d adapted to be displaced by said am lifying levers about two rectangular axes, t e movement on one axis corresponding to the expansion of the test piece, and the movement on the other axis corresponding to the difference between the expansion of the test piece and the standard piece, a rod mounted on said tripod, a pen secured to said rod, and means for recording the successive positionsof the pen.

.2. A differential dilatometer, comprising a device containin a standard piece and a test piece, ampli ying levers which are acted upon by the said pieces during their expansion, a tripod-which is displaced by the amplifying levers in such manner that the said tripod is moved according to two rectangular axes, the movement on one axis corresponding to the expansion of the test piece, whilst the movement on the other axis corresponds to the difference between the expansion of the test piece and the standard iece, a pen which is secured to a rod mounte on the said tripod, a recording board which is brought into contact with the said pen at regular intervals, and means imparting an alternating movement to thesaid recording board.

3. A differential dilatometer comprising means adapted to contain a standard piece and a test piece, a plurality of sets of amplifying levers which are separately acted upon by the respective pieces, means whereby the compound action of the sets of .amplifying levers may be afiected, the said means being adapted for the displacement of an element according to two axes, a rod which carries a tracing member and is secured to the said element, and mechanical devices for rcording the movements of the said tracing membe o In testimony that I claim the foregoing as my invention,I have signed my name hereto.

PIERRE CHEVENARD. 

